1. Field of the Invention
The present invention relates to a device mounting board, and a semiconductor module and a manufacturing method therefore.
2. Description of the Related Art
In recent years, with miniaturization and higher performance in electronic devices, demand has been ever greater for further miniaturization of semiconductor devices used in the electronic devices. With such miniaturization of semiconductor devices, it is of absolute necessity that the pitch of electrodes to enable mounting on a wiring board be made narrower. A known method of surface-mounting a semiconductor device is flip-chip mounting in which solder bumps are formed on electrodes of the semiconductor device and the solder bumps are soldered to an electrode pad of the wiring board. With this flip-chip method, however, there are restrictive factors for the narrowing of the pitch of electrodes, such as the size of the solder bump itself and the bridge formation at soldering. As one structure used to overcome these limitations, known is a structure where a bump structure formed on a substrate is used as an electrode or a via, and the electrodes of the semiconductor device are connected to the bump structure by mounting the semiconductor device on a substrate with an insulating resin layer, such as epoxy resin, held between the semiconductor device and the substrate.
However, since copper and other metals which have conductivity are generally used as a material that forms the bump structure, the bump structure and the insulating resin layer have different coefficients of thermal expansion from each other. For that reason, heat stress occurs at an interface between the bump structure and the insulating resin layer as a result of a temperature change in a heat treatment or usage environment. Thus there is concern that the adhesion between the bump structure and the insulating resin layer may deteriorate. Also, there is concern that the connection reliability between the bump structure and the electrodes of the semiconductor device may deteriorate.